A settlement can only be raided once per day by anybody. For example, if Vekaro was to be raided by Kal'Arkon, that would be it for that day. No more raids on Vekaro. So how would someone know if a settlement got raided already?
Cities with a clear gatehouse tend to leave up a sign at the entrance telling people when it can be raided again. With Vekaro though, there's no real entrance. So I guess they'd have to put it up on a notice board or something.
